A Case of Severe Hypernatremic Myopathy by Primary Hypodipsia, Hyperglycemic Hypertonic State in a 17-Year-Old Patient With Mental Retardation

Abstract

Although severe hypernatremia, defined as a sodium concentration > 180 mEq/L, is associated with a high mortality rate, particularly in adults, little is known about severe hypernatremia in patients with diabetic ketoacidosis (DKA). Hypernatremic myopathy has been reported in patients with severe dehydration, acute kidney injury, and rhabdomyolysis. Dehydration in a diabetic patient with mental retardation may be caused by osmotic diuresis and exacerbated by hypodipsia, which requires the patient to be educated about regular oral hydration. Here, we describe a 17-year-old patient with reversible severe hypernatremia (serum corrected sodium, 180 mEq/L) and primary hypodipsia, but without DKA. The patient visited the emergency room due to agitation and weakness in both lower extremities. Initial laboratory tests showed hyperglycemia, acute kidney injury, acute hepatitis, and myopathy. Following rehydration with one-quarter isotonic saline and intensive insulin therapy, the patient’s symptoms (including leg weaknesses) and laboratory findings improved.